The above valve opening/closing timing control device, ordinarily, changes the relative rotation phase of the driven-side rotating body with respect to the drive-side rotating body by switching a supply destination of a working fluid that was discharged from a fluid pump to an advance chamber or a delay chamber by operation of an electromagnetic valve.
The relative rotation phase is changed to an advance side when the working fluid is supplied to the advance chamber, and the relative rotation phase is changed to a delay side when the working fluid is supplied to the delay chamber.
The optimal opening/closing timing of the intake valve or the exhaust valve differs depending on the running circumstances of the engine, such as when starting the engine or during vehicle running. For example, it is possible to set the opening/closing timing of the intake valve or the exhaust valve to a timing that is optimal when starting the engine by restricting the relative rotation phase during an engine stoppage to an intermediate lock phase between a most advanced phase and a most delayed phase.
Patent Document 1 and Patent Document 2 disclose a valve opening/closing timing control device provided with a fluid pressure chamber formed as a section between a drive-side rotating body and a driven-side rotating body, an advance chamber and a delay chamber formed by dividing a fluid pressure chamber with a dividing portion, an advance channel that supplies/drains a working fluid to/from the advance chamber, a delay channel that supplies/drains the working fluid to/from the delay chamber, an intermediate lock mechanism capable of switching between a locked state that restricts a relative rotation phase of the driven-side rotating body with respect to the drive-side rotating body to an intermediate lock phase and an unlocked state in which the restriction has been released, and an electromagnetic valve capable of switching a supply destination of working fluid that has been discharged from a fluid pump to the advance chamber or the delay chamber by a power source switching on/off.
With the electromagnetic valve provided in the valve opening/closing timing control device in Patent Document 1, the supply destination of the working fluid that has been discharged from the fluid pump is switched to the delay chamber when the power source switches off.
With the electromagnetic valve provided in the valve opening/closing timing control device in Patent Document 2, the supply destination of the working fluid that has been discharged from the fluid pump is switched to the advance chamber when the power source switches off.